Just Can't Get Enough
by CameronZinner
Summary: The last time he had tried ogling his step-sister at the dinner table Marti had exposed him and he was almost humiliated. But Derek Venturi never gets humiliated. Derek Venturi always gets what he wants. And right now, he wanted Casey. Dasey one-shot. M for explicit sexual content and some bad language! Please review!


**Disclaimer:** I put this together on a whim so please forgive me if it sounds rushed or if there are minor grammatical errors. Enjoy! (Oh, and I don't own Life with Derek or any of the characters. Obviously!) This fic probably takes place towards the end of the series, but I didn't really have a time frame in mind when I wrote this. And _please _feel free to leave a review! I love to hear feedback!

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**Just Can't Get Enough**

Derek shifted uncomfortably on the kitchen stool as he eyed his step-sister lustfully from head to toe. Casey, on the other hand, was too engrossed to notice that he was staring; Saturday was her self-designated workout day, and she wasn't going to let it go to waste keeping Derek in line.

She was in full exercise garb - complete with a trendy track suit and a yoga head-band - which only made things worse for the aroused teen whose mouth was now embarrassingly agape.

_Girls, girls, GIRLS!_ was all that was on his mind. He hadn't seen any action for a while, and his raging hormones were taking a toll on him no impromptu jerk-off session could cure. Derek's gaze was fixed on Casey's voluptuous behind as if he was closing in on prey. He secretly wished she would wear her tight-fitting track pants every day of the week (it would perhaps suffice until he could get a release). No one else was home but the two of them, and this only made things easier for him. The last time he had tried ogling her cleavage at the dinner table Marti had exposed him and he was _almost_ humiliated. But Derek Venturi never gets humiliated. Derek Venturi _always_ gets what he wants. And right now, he wanted Casey.

Casey had her back turned to Derek, and was trying to pry open the lid of the blender to get her strawberry protein shake going. She clawed at the plastic, even used the tips of her nails to try and loosen the damned thing, but it just wouldn't budge. Derek chuckled, and took another sip of his soda.

Casey turned her head sharply and looked Derek square in the eye. Her headband was pretty much soaked, and so was the rest of her hair, and pretty much her whole face. To Derek, it looked as though she had just taken a shower. He snickered even more.

"What are you laughing at?" Casey snapped, pausing to grunt as she tried to get the lid open.

Feeling defeated, she lifted the blender to the kitchen island where Derek was seated and continued her efforts. Her chest was in full view, and Derek couldn't get enough. It was obvious she wasn't wearing a bra, because if she was, he wouldn't have been able to locate her nipples with such precision. An erection sprung in his sweat pants, and instead of fighting the feeling he let it sit there, rigid and proud.

"For a person who works out religiously, you sure don't have any muscle."

"I'd like to see you try," Casey retorted. With one last attempt, the lid popped open and she momentarily lost her balance.

"Easy there, Case," Derek said, taking a cocky sip of his soda before getting up and walking past Casey to the fridge.

Casey rolled her eyes. She grabbed a handful of fresh raspberries and released them, one by one, into the tall glass body of the stubborn blender. "Don't you have somewhere to be?"

Derek inspected the contents of the fridge, and settled for a carton of milk. He took a whiff to see if it was any good, and then chugged it down - trails of white liquid running down his cheeks. He stopped, wiped his face with his wrist, and replied to Casey's snarky remark. "All of the guys have girlfriends now and they're probably fucking each other's brains out as we speak. I could be out doing the same thing, but no, I've chosen the good path and have decided to spend some quality time at home with you."

"Your obscene language isn't welcome in my kitchen."

"Please keep in mind that this used to be _my _kitchen."

Casey ignored his comment and plucked the leaves meticulously off of each round and plump strawberry. With the milk carton in hand, Derek closed the fridge with his bare foot, walked over to Casey, and took a peek inside the blender. He pressed his shoulder against hers, and was so fixed on making her life as difficult as possible that he contemplated turning on the blender and releasing an explosion of pink liquid all over Casey. She's dumb enough, he thought, to leave it plugged in while the top was open, so in a way he would be teaching her a valuable lesson.

"DER-EK!"

He hadn't realized he had spilled some milk onto Casey whilst peering over the glass edge into the blender. Her chest was damp and Derek was quick to gaze at the outline of her breasts underneath the polyester.

"This is a NEW shirt! Ugh! What's gotten into you today? You're obnoxious, YES, but now you're just being flat out annoying. And I thought I told you you aren't welcome in here." Casey grabbed a dish towel and patted her chest dry, while muttering half-constructed sentences under her breath in anger.

"Oh _please _Case. You spend twenty minutes doing what you call 'exercise' and then think you're better than all of us with your expensive yoga clothes and your fancy protein shakes. _Oooo, look at me," _he said, imitating Casey's voice and flinging his hands in the air, "_I'm Casey McDonald and I'm so healthy and I'm so perfect. _If anything, _I_ should be the one throwing the fruits into this blender. Lucky for me, I've got the metabolism of an Olympic athlete and don't need these girly smoothies."

"Derek, you've been on my case the whole day. You know, if you tell me what's up I might be able to help you." Casey paused. "Wow, I can't believe I just said that."

Derek took a long hard look at the window, and then looked quickly at Casey who was moving the blender back to the counter. "If I make this request will you _honestly_ follow through with it if it means I get off your case?"

"Yes, of co-" Casey stopped mid-sentence, realizing that she didn't want to be making any promises just yet. "I'm listening."

Derek faced Casey and looked her right in the eye. If he backed down now, he would be doomed to spend the rest of the day figuring out how to jack off in the privacy of his room without drawing too much attention. It just wasn't worth it.

"Casey, I'm horny and I need a release. I haven't fucked a girl in forever and if you don't help me now I _swear_ I will explode and that isn't gonna be pretty!"

Derek closed his eyes and flinched, preparing to shield himself from Casey's impending punches. But to his surprise, not a single punch was thrown. Not even a spank on the shoulder.

"Okay." Casey said coolly. "But only if your willing to do my chores for four months."

Derek was surprised she had even considered his request. But he wasn't so keen on the terms and conditions.

"Three months."

"I'm not going any lower than four."

"Fine. How does three months and an extra month of free rides sound?"

"Do you want me to make it five?"

"No, no. Okay, fine. How about three months of chores and...and I do your laundry."

"Throw in the free rides as well and its a deal."

"You're killing me here, Case."

"Do you want me to fuck you or not?"

"Yes, Casey, yes but I _can't_ drive you around. Please, let's just leave it at that."

"You sound like a poor little puppy, begging like that, " Casey said condescendingly. "I think I'm going to savor this moment..."

"Okay, I'll do three and a half months of chores and laundry, but NO free rides. I can't be seen riding around with you in public."

Casey raised her eyebrows and placed her hands on her hips. "I don't like that tone..."

"Okay okay I'll do the free rides."

"And clean my room for a month as well."

"CASEY!"

"You know what, I don't want you going through my stuff anyways. I'll take you up on your deal...unless you don't mind letting me sit in your chair for a few months as well."

Casey was going to take advantage of the circumstances as much as she possibly could. Derek, on the other hand, was growing impatient. The tension was building up within him and the heated bargaining was almost enough to make him ejaculate.

"OKAY I will let you do whatever you want but just _please_ don't leave me hanging here. My penis is too invested to back out now - I can almost hear it _crying_!"

"Okay, fine. So that's three months of lau-"

"YES! I GET IT! NOW WILL YOU JUST LET ME FUCK YOU?!" Derek said, exasperated and his face turning red.

"Relax. I'm fine with the deal. Deal?"

"Deal."

The horny teen grabbed his t-shirt and yanked it violently over his head, revealing his bare torso. He wriggled it off of his arm and chucked it to the corner of the kitchen.

Derek certainly had some clear definition of muscle, but it wasn't anything to drool over. His shoulders were lanky and his collar bones protruded out of his hairless pale chest, but he still had a discernible set of pecs and an adequate six pack. He stood impatiently over Casey and motioned for her to take her shirt off, and she grinned at the sight of her squirming half-naked step-brother.

"I thought you said you had an 'athlete's metabolism'..."

"I got too lazy and stopped working out - get over it," he said impatiently. "Now _please_ take that shirt off so we can get going with our deal."

Casey took her own time to undress. To Derek, this was a release. But to Casey, it was simply another way of getting him to shut-up.

She tossed her headband on the counter. Her shirt was drenched in perspiration and clung to her body, but she slipped her fingers delicately under the hem and slid it over her head in one swift movement.

Derek had already taken off his sweatpants and boxers at this point, and stood nude in Casey's presence. His cock was fully erect, and his eyes were fixed on the sight before him. Casey's breasts were round and supple and firm - and were definitely on the larger end of the size spectrum. They beckoned him, and he felt his heart skip a beat every time they jiggled. He had definitely seen his share of tits, that were either too small they were barely there, or too large and droopy that he almost wished they weren't. But never had he seen such a perfect balance of plumpness and roundness. He could feel pre-cum glaze the head of his dick, and he cupped his balls in the palm of his left hand, while slowly stroking his manhood with his right.

She teased him knowing her tits were his weakness, and circled her nipples with the tips of her fingers.

"What is that, six and a half? Seven? I really wasn't expecting that from you..." she said, looking down at his throbbing member.

"Casey! Enough's enough." Derek said, tilting his head back in utter frustration. The tension was building and he wasn't sure he would be able to hold any longer.

"Would it kill you to play along?"

She sighed, and then slipped off her track pants. She loosened her thong and let it fall gracefully to her ankles, and soon enough the two of them were both standing nude in the afternoon light that streamed into the kitchen. Casey knew all eyes were on her, so she tried to be as seductive as she could and did a quick turn-around to flaunt her tan body.

Derek whimpered in pleasure as he caught sight of her bare ass and then the hairless beauty that was her pussy, and continued running his palm along the length of his erection. As soon as Casey had made the full turn, Derek moved in terribly fast, grabbed her shoulders, and was prepared to kiss her like he had never kissed any girl before. Casey, still locked in his embrace, dodged his attempt at a smooch.

"Don't even think about planting one on me with those chapped lips of yours."

Derek obliged. Still pressed against her sweaty body, he moved his lips lower as per her request and kissed her neck with rage. Casey could feel his cock against her thigh, and gripped onto his body with tight arms. He cupped her breasts with his hands and squeezed them as his mouth grew even more furious. He came up for a breath, and then moved his mouth lower down her chest until he was sucking and nibbling hungrily on her right tit. Derek's free hand was busy stroking his step-sister's pussy, and when he slipped his index finger into her hole, Casey moaned wildly in pleasure.

"D-d-d-er-EK!"

Derek grunted and spoke inaudibly into the roundness of her breast, and she dismissed it as a muffled groan of pleasure and gripped his body even tighter.

He pulled away, letting out a huge heave of exhaustion, and held her by the hips.

"You need to take care of my cock, Case. I swear it's gonna stab one of us if gets any harder."

Before he could finish, Casey inched her way down his body and left a trail of kisses on her way down to the main prize. She pushed Derek against the edge of the kitchen island and got on her knees. The head of his glistening penis was staring right at her, and she kissed the tip delicately with her supple lips.

"CASEY! Stop teasing and get to work! It's not gonna suck itself!"

She took hold of Derek's warm, pulsing manhood and pumped. Derek groaned. She swirled her tongue around the tip, and felt the salty taste of his pre-cum linger in her mouth.

"C'mon Case, I know you can do better than that," Derek said with his buttocks pressed against the edge of the island and his hands gripped for support. "I'm sure you've done this many times," he said, and then smirked.

Without any warning, she went in for the kill. Casey slipped her wet mouth over the throbbing cock and bobbed her head on her step-brother's boner as vigorously as she could. _That'll show him_, she thought.

"Aaaaah - " Derek gasped, tilting his head back. "Oh fuck, fuck, Casey...mmm..." Derek tried to push his boner as far as he could into Casey's expectant mouth, and placed both his hands on the back of her head to guide her as she bobbed back and forth.

"Yeah Casey...fuck...yeah...mmmm.."

This was far more than he had ever asked for, but if he was going to make the most of this opportunity she was going to have to do a lot more than a blowjob. Derek tapped Casey on the ear, and she looked up at him with furled eyebrows and his throbbing dick still in her clutches.

"I was doing fine, wasn't I?"

Derek smiled mischievously "Sure, it was alright." he shrugged his shoulders. "But I was kinda hoping to spice things up a little bit." Casey, who was now standing upright, crossed her arms over her breasts and looked at Derek with a look of confusion.

"Well, what more do you want?"

Derek hastily cleared the kitchen island of the empty bowls and dish towels and the odd plate and a half-full carton of orange juice, until it was bare.

"Ta-da!" he said, with a wide grin on his face and his hands stretched as though he were showing off a brand-new car.

"I don't get it."

"Did you really think a blowjob was gonna to be enough? Please, Casey. And a lousy one at that." He shook is head, and feigned his disappointment in her 'clear lack of dick-sucking capabilities'.

"That was NOT lousy, Derek. In fact, I put a lot of effort into that and I could tell you were obviously enjoying it."

Derek dismissed the comment. He climbed onto the kitchen island and laid down as seductively as he could on his back. If he was any taller, his bare feet would have been dangling off the edge. He looked to Casey with his member in his right hand, and smiled eagerly.

"Ew, Derek, we eat food here, and now you've probably infected it with whatever's lurking in your butt."

"Are you going to join me up here or what?"

Casey rolled her eyes. She climbed onto the island and positioned herself in a cowgirl position on top of Derek - who was lying down casually with his hands behind his head.

"If it shuts you up..."

Derek held his hard-on as he guided into Casey's pussy, and moaned as it slid in with ease.

With both hands cupping her breasts and her back arched forward, Casey straddled Derek's body with her legs and began to bounce angrily on his cock.

"Y-y-y-y-es Casey. Fuck-fuck-fuck-fuck yes" Derek held onto Casey's thighs as the bouncing became more vigorous, and could feel himself reaching the edge.

"Shit-shit-shit-I-re-aliZED-FUCK-DER-EK!" Casey moaned and panted as she tried her best to finish her sentence. She wasn't even sure if Derek was listening to her, as he looked as though he was in a trance with his eyes rolled back and his mouth slightly open. "I-realiz-ed-you-aren't-WEAR-ing-a-cond-om." She stopped her rhythmic bouncing and held onto his chest for support.

Derek groaned and stretched his arms out to his sides. "You always find a way to be a buzzkill."

"Are you _trying _to get me pregnant? Because if that's what this is all about then forget it, Derek. And your knobby knees keep knocking against my spine."

Afraid she would leave him half-way through, Derek grabbed her hips and held them tight. "Fine, fine, finish me off with your mouth."

Casey quickly unmounted and held the pulsating member in her hand. She placed her mouth on the thick shaft and was determined to suck it dry.

"Fuck...fuck...Casey...I'm gonna come...Casey I'm gonna...I'm gonna...CUM-OHHH!"

Derek's body shook intensely and released an ample cascade of creamy white cum into Casey's unsuspecting mouth. The sheer amount of jizz was too much for her too handle, and when she pulled off a final shot of semen hit Casey straight in the eye.

"DER-EK!" she exclaimed, with Derek's seed dripping down the corner of her mouth. "MY EYE!"

Derek laid back with hands behind his head on the island, staring up in the ceiling and reveling in the after-glow of his invigorating orgasm. His penis was flaccid, and just lay trembling on his stomach. He was exhausted.

"What can I say, I have good aim," he replied smugly.

"I swear, if you got any in my hair..." Casey said, leaving her sentence unfinished as she hopped off the island. She grabbed the clothing she had shed on the ground and walked out of the kitchen. Derek propped himself up on his elbows to get a good look of Casey's ass as she left.

"It's definitely not the first time."

"You're unbelievable!" he heard Casey yell from the corridor.

Derek swung his bare feet over the side of the island and let them dangle freely. He felt at ease for the first time, and rubbed the inside of his thighs before hopping off.

He knew he would be uncontrollably horny again in a matter of hours, but that wouldn't be a problem. He would simply work out another deal with Casey and she would give into his charm as usual. You know why?

Because Derek Venturi _always _gets what he wants.


End file.
